Podcast
Questions and Answers
What percentage of fat is found in cow's milk according to the given definition?
What percentage of fat is found in cow's milk according to the given definition?
Which of the following is the main component of milk?
Which of the following is the main component of milk?
What is the primary form of fat found in milk?
What is the primary form of fat found in milk?
Which nutrient makes up around 5% of the composition of milk?
Which nutrient makes up around 5% of the composition of milk?
Signup and view all the answers
The colloidal suspension of proteins in milk primarily consists of which type of proteins?
The colloidal suspension of proteins in milk primarily consists of which type of proteins?
Signup and view all the answers
Which of the following animal species contributes significantly to milk production in the Mediterranean countries?
Which of the following animal species contributes significantly to milk production in the Mediterranean countries?
Signup and view all the answers
What type of emulsion is milk classified as?
What type of emulsion is milk classified as?
Signup and view all the answers
Which mineral is found in milk, albeit in small quantities?
Which mineral is found in milk, albeit in small quantities?
Signup and view all the answers
Which microorganism is primarily responsible for souring in milk?
Which microorganism is primarily responsible for souring in milk?
Signup and view all the answers
What is primarily caused by lactic acid bacteria dropping the pH below 4.6?
What is primarily caused by lactic acid bacteria dropping the pH below 4.6?
Signup and view all the answers
Which group of microorganisms is associated with gas production in milk spoilage?
Which group of microorganisms is associated with gas production in milk spoilage?
Signup and view all the answers
What is the most crucial step in controlling psychrotrophs in milk?
What is the most crucial step in controlling psychrotrophs in milk?
Signup and view all the answers
Which of the following is NOT a recommended practice to control microbial growth in raw milk?
Which of the following is NOT a recommended practice to control microbial growth in raw milk?
Signup and view all the answers
Which organism is commonly associated with proteolysis in spoiled milk?
Which organism is commonly associated with proteolysis in spoiled milk?
Signup and view all the answers
Which bacteria are primarily responsible for lipolysis in milk?
Which bacteria are primarily responsible for lipolysis in milk?
Signup and view all the answers
What type of soil is primarily found in dairy facilities that must be removed during cleaning?
What type of soil is primarily found in dairy facilities that must be removed during cleaning?
Signup and view all the answers
What is the result of proteinase activity in milk?
What is the result of proteinase activity in milk?
Signup and view all the answers
Which of the following factors is critical for preserving milk quality after it leaves the cow?
Which of the following factors is critical for preserving milk quality after it leaves the cow?
Signup and view all the answers
Psychrotrophs in milk primarily pose a risk under which condition?
Psychrotrophs in milk primarily pose a risk under which condition?
Signup and view all the answers
What effect does a reduction in temperature below the minimum necessary for microbial growth have on microorganisms in milk?
What effect does a reduction in temperature below the minimum necessary for microbial growth have on microorganisms in milk?
Signup and view all the answers
Which of the following enzyme activities can lead to rancidity in milk?
Which of the following enzyme activities can lead to rancidity in milk?
Signup and view all the answers
Which of the following Gram-negative bacteria can be found in raw milk that causes spoilage during refrigerated storage?
Which of the following Gram-negative bacteria can be found in raw milk that causes spoilage during refrigerated storage?
Signup and view all the answers
What is a consequence of enzyme activity from psychrotrophs in milk?
What is a consequence of enzyme activity from psychrotrophs in milk?
Signup and view all the answers
Which of the following substances may be formed when lactose is fermented?
Which of the following substances may be formed when lactose is fermented?
Signup and view all the answers
What is the role of thiocyanate in the LP system for preserving raw milk?
What is the role of thiocyanate in the LP system for preserving raw milk?
Signup and view all the answers
At what temperature can raw milk be kept for a few days without spoilage when properly preserved?
At what temperature can raw milk be kept for a few days without spoilage when properly preserved?
Signup and view all the answers
What concentration of hydrogen peroxide is recommended to activate the LP system in milk?
What concentration of hydrogen peroxide is recommended to activate the LP system in milk?
Signup and view all the answers
How long can preserved milk last at 30°C after the addition of thiocyanate and hydrogen peroxide?
How long can preserved milk last at 30°C after the addition of thiocyanate and hydrogen peroxide?
Signup and view all the answers
What is the effect of hydrogen peroxide on raw milk's keeping quality?
What is the effect of hydrogen peroxide on raw milk's keeping quality?
Signup and view all the answers
Which factor does NOT influence the effectiveness of hydrogen peroxide as a preservative?
Which factor does NOT influence the effectiveness of hydrogen peroxide as a preservative?
Signup and view all the answers
What is the minimum required concentration of thiocyanate for effective milk preservation?
What is the minimum required concentration of thiocyanate for effective milk preservation?
Signup and view all the answers
How do bacteria in milk contribute to the LP system?
How do bacteria in milk contribute to the LP system?
Signup and view all the answers
What is the primary purpose of microbial cleaning in dairy operations?
What is the primary purpose of microbial cleaning in dairy operations?
Signup and view all the answers
Which temperature range is considered effective for hot water sanitation in dairy plants?
Which temperature range is considered effective for hot water sanitation in dairy plants?
Signup and view all the answers
What is a key factor that limits the effectiveness of chemical sanitizers?
What is a key factor that limits the effectiveness of chemical sanitizers?
Signup and view all the answers
Why is it important to cool milk quickly after it leaves the udder?
Why is it important to cool milk quickly after it leaves the udder?
Signup and view all the answers
What is a benefit of low-temperature storage of milk?
What is a benefit of low-temperature storage of milk?
Signup and view all the answers
In spray cooling, how is the milk kept at a low temperature?
In spray cooling, how is the milk kept at a low temperature?
Signup and view all the answers
What type of cooler consists of a coil that circulates chilled water to cool the milk?
What type of cooler consists of a coil that circulates chilled water to cool the milk?
Signup and view all the answers
What is the common temperature of milk when it leaves the udder?
What is the common temperature of milk when it leaves the udder?
Signup and view all the answers
Study Notes
Overview of Milk
- Milk is a secretion from female mammals, primarily cows, consumed worldwide.
- U.S. Public Health Service defines cow's milk composition: minimum 8.25% milk solids not fat, and 3.25% fat.
- Cow's milk represents the majority of milk available for human consumption; sheep and goats also contribute significantly in some regions.
Composition of Milk
- Milk is a complex food, mainly consisting of water (dominant), fats (3.9%), proteins (3.3%), lactose (5%), and minerals (0.7%).
- Contains over 100,000 molecular species, including vitamins (A, C), enzymes (like lactoperoxidase), and somatic cells.
- Four main types of enzymatic activity in milk: lactose fermentation, lipid hydrolysis, protein breakdown, and phospholipase activity affecting fat globules.
Microbial Growth and Quality Preservation
- Quality maintenance relies on cleanliness, sanitation, and careful handling post-milking.
- High temperatures during milking favor microbe growth; rapid cooling slows this down.
- Raw milk can harbor heat-susceptible pathogens and spoilage microorganisms, emphasizing the importance of temperature control.
Psychrotrophic Microorganisms
- Psychrotrophs, which can thrive at low temperatures, are problematic for dairy products, leading to spoilage.
- Common psychrotrophic organisms include both Gram-negative (e.g., Pseudomonas) and Gram-positive bacteria (e.g., Bacillus).
Types of Spoilage in Milk
- Souring: Caused by lactic acid bacteria.
- Casein precipitation: Occurs when pH drops below 4.6.
- Gas production: Driven by Clostridium and Bacillus.
- Proteolysis and lipolysis: Result from several spoilage bacteria, notably Pseudomonas.
Prevention and Control Measures
- Cleaning and Sanitizing: Essential for maintaining milk quality, reducing psychrotroph counts.
- Cooling Techniques: Immediate reduction of temperature after milking is crucial; methods include spray and immersion cooling.
-
Hydrogen Peroxide and Lactoperoxidase Systems: Used in specific conditions to extend shelf life, particularly in regions lacking refrigeration.
- Ideal concentrations include 10-15 ppm of thiocyanate and 300-800 ppm of hydrogen peroxide for preservation.
Summary of Antimicrobial Measures
- Maintaining low temperatures significantly extends the storage life of milk.
- Use of cleaning agents is critical, with chlorine and iodine-based sanitizers commonly employed in the dairy industry.
- Effective sanitation involves both mechanical cleaning and chemical disinfection.
Enzyme Activity Impact
- Enzymatic spoilage can lead to undesirable flavor changes and texture alterations in milk, influenced by enzyme-producing microbial activity.
- Understanding microbial action on milk is vital for quality control in dairy production.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz explores the composition of milk, focusing on its nutritional components and microbial quality preservation. It covers the key constituents such as fats, proteins, and vitamins found in milk, as well as the importance of sanitation and temperature control. Perfect for students studying food science or dairy production.
